This randomized phase III trial studies carboplatin and paclitaxel to see how well they work with or without cisplatin and radiation therapy in treating patients with stage I-IVA endometrial cancer. Drugs used in chemotherapy, such as carboplatin, paclitaxel, and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving chemotherapy and radiation therapy after surgery may kill any tumor cells that remain after surgery. It is not yet known whether carboplatin and paclitaxel are more effective with or without cisplatin and radiation therapy in treating patients with endometrial cancer.

PRIMARY OBJECTIVES: I. To determine if treatment with cisplatin and volume-directed radiation followed by carboplatin and paclitaxel for 4 cycles (experimental arm) reduces the rate of recurrence or death (i.e., increases recurrence-free survival) when compared to chemotherapy consisting of carboplatin and paclitaxel for 6 cycles (control arm) in patients with stages III-IVA endometrial carcinoma (\< 2 cm residual disease) or patients with International Federation of Gynecology and Obstetrics (FIGO) 2009 stage I or II serous (uterine papillary serous carcinoma \[UPSC\]) or clear cell endometrial carcinoma and positive cytology. SECONDARY OBJECTIVES: I. To determine if treatment with cisplatin and volume-directed radiation followed by carboplatin and paclitaxel for 4 cycles (experimental arm) reduces the rate of death (i.e., increases survival) when compared to chemotherapy consisting of carboplatin and paclitaxel for 6 cycles (control arm) in patients with stages III-IVA endometrial carcinoma (\< 2 cm residual disease) or patients with FIGO 2009 stage I or II serous (UPSC) or clear cell endometrial carcinoma and positive cytology. II. To compare the regimens with respect to acute and late adverse effects of therapy. III. To determine the impact of patient-reported quality of life during and following treatment for up to 1 year with the two treatment regimens. TERTIARY OBJECTIVES: I. To bank formalin-fixed, paraffin-embedded (FFPE) tumor tissue and whole blood specimens for future research. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive cisplatin intravenously (IV) on days 1 and 29. Patients also undergo radiation therapy once daily (QD), 5 days a week, for 5-6 weeks. Some patients may then undergo brachytherapy over 2-3 weeks. Beginning within 8 weeks after completion of chemoradiotherapy, patients receive paclitaxel IV over 3 hours and carboplatin IV on day 1. Treatment repeats every 21 days for 4 courses in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive paclitaxel IV over 3 hours and carboplatin IV on day 1. Treatment repeats every 21 days for 6 courses in the absence of disease progression or unacceptable toxicity. After completion of study therapy, patients are followed up every 3 months for 2 years, every 6 months for 3 years, and then annually thereafter.